Method of interconnecting two coaxial tube systems

ABSTRACT

Method of interconnecting two coaxial tube systems, each having at least two corrugated coaxial tubes, by providing innermost tubes of the two systems to be interconnected and at slightly smaller or larger diameter, respectively in or on the end portions of the said two innermost tubes in corrugation contour matching and fitting relation; bonding the axial ends of the first sleeve or of the two innermost tubes respectively to the two innermost tubes or both first sleeves; telescoping a second sleeve of slightly smaller or larger diameter than the next, outer tubes of each system in corrugation receiving relation to the axially displaced ends of the outer tubes, bonding the second sleeve to the outer tubes.

United States Patent [191 Ziemek et al.

METHOD OF INTERCONNECTING TWO COAXIAL TUBE SYSTEMS Inventors: GerhardZiemek, I-lannover;

Friedrich Schatz, Langenhagen, both of Germany Kabel-und MetallwerkeGutehoifnungshutte Aktiengesellschaft, Hannover, Germany Filed: Sept.15, 1971 Appl. No.: 180,796

Assignee:

Foreign Application Priority Data Sept. 21, 1970 Germany P 20 46 331.4

References Cited UNITED STATES PATENTS Borden et al. 156/158 X [4 1 Aug.21, 1 973 FOREIGN PATENTS OR APPLICATIONS 62,953 7/1892 Germany 138/120987,514 3/1965 Great Britain 156/49 Primary Examiner-Richard B. LazarusAttorney-Ralf H. Siegemund et al.

[57] ABSTRACT Method of interconnecting two coaxial tube systems, eachhaving at least two corrugated coaxial tubes, by providing innermosttubes of the two systems to be interconnected and at slightly smaller orlarger diameter, respectively in or on the end portions of the said twoinnermost tubes in corrugation contour matching and fitting relation;bonding the axial ends of the first sleeve or of the two innermost tubesrespectively to the two innermost tubes or both first sleeves;telescoping a second sleeve of slightly smaller or larger diameter thanthe next, outer tubes of each system in corrugation receiving relationto the axially displaced ends of the outer tubes, bonding the secondsleeve to the outer tubes.

10 Claims, 2 Drawing Figures Patented 21, 1973 2 Sheets-Sheet 1 PatentedAug. 21, 1973 2 Sheets-Sheet z 1 METHOD OF INTERCONNECTING TWO COAXIALTUBE SYSTEMS The present invention relates to a method forinterconnecting coaxial tube or pipe systems; it is assumed that theindividual tubes of each system are corrugated, and the invention isparticularly directed to coaxial interconnecting, high frequency cablesor cables with superconductive conductors contained in corrugatedtubular envelopes.

The interconnection of coaxial tube systems wherein the individual tubesare corrugated is complicated because of the corrugation. Corrugationis, however, a very desirable feature for reasons of flexibility,permitting reeling of the tubing even if having relatively thick walls.The end-to-end connection between such tubes.

shall be of sufficient mechanical strength, and if the tubes serve asconductor, an electrically satisfactory connection is to be made betweenthem and maintained. Previously high frequency cables of the coaxialtube variety with corrugated, tubular conductors have beeninterconnected by means of special plug and connector elements.Particular connectors were individually connected to the tubularconductors, and connectors on different tubes were then interconnected.Of course, such plug elements require very accurate manufacturing, andthey increase cost of the entire system particularly because the plugand connector elements are separate auxiliary components in the natureof accessories.

It is the object of the present invention to provide method whichpermits the connection of coaxial tube systems at high mechanicalstrength and low cost while satisfactory electrical connection as neededin case of cables, is ensured. In accordance with the method of thepresent invention, the several coaxial tubes of a coaxial tube systemare interconnected in stepwise fashion beginning by interconnecting theinnermost tubes by means of a sleeve having matching corrugationpattern, but slightly larger or smaller diameter than the innermosttubes. The sleeve is seated on or inserted into the ends of the twotubes and bonded, e. g soldered or welded thereto. Axially aligned tubesof next larger diameter of the two systems, are interconnectedanalogously, so that progressively tubes to be interconnected areinterconnected indirectly by means of an overlapping or inserted sleeve.

The advantage of the invention is to be seen in that upon utilizing suchconnector sleeve of similar corrugation pattern as the tubes themselves,a mechanically strong and firm connection is almost automaticallyestablished. Soldering or welding, of course, aids in the establishingof the mechanical connection, but the primary purpose of such bonding isto provide also for an electrically satisfactory connection. Anotheradvantage of the invention is to be seen in that as a consequence ofmaking the connection the diameter of the tube system is onlyinsignificantly changed so that after providing a protectivecoating orjacket onto the outermost tube of the system the joint is no longer orhardly visible. Also, it can readily be seen that phase coherency of thecorrugation pattern through the joint is inher ently provided for theconnectior sleeves, so to speak, continued the phase from one tube tothe next one.

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter which is regarded as theinvention, it is believed that the invention, the objects andfeatures'of the invention and further objects, features and advantages Ithereof will be better understood from the following description takenin connection with the accompanying drawings in which:

FIG. 1 illustrates schematically a cross section view through a coaxialhigh frequency cable system interconnected in accordance with thepreferred embodiment of the present invention;

FIG. 2 illustrates a similar section view with a modifcation of theinterconnection as provided.

Proceeding now to the detailed description of the drawing, referencenumerals l and 3 respectively denote inner and outer tubes of a firstcoaxial tube system to be interconnected with a second system thatincludes tubes 2 and 4. In particular, I and 2 constitute the innerconductors of two high frequency cables to be interconnected and tubes 3and 4 are the respective outer conductors. A helical spacer 5 isprovided between tubes 1 and 3 to maintain coaxial position betweenthese tubes. Analogously, a spacer 5' is provided to coaxially positiontube 4 on tube 2. Therefore, a concentrical relationship is establishedin each of the two tubular conductor systems.

In the particular example illustrated, all of the tubes are corrugatedwhereby in particular all tubes are provided with helical corrugation.Corrugation is needed for each tubular conductor system to havesufficient flexibility. Now, it is assumed that the tube system l-3 isto be connected to the system 2-4, whereby in particular, of course,inner tubes 1 and 2 are to be interconnected and outer tubes 3 and 4 arelikewise to be interconnected separately. This interconnection iscarried out as follows.

First of all, a portion of the outer conductors 3 and 4 is cut off sothat the particular ends of tubes 1 and 2 to be interconnectedrespectively, protrude from tubes 3 and 4; the several tubes areactually shown in this fashion in FIG. 1. Next, a sleeve 6 is providedhaving these characteristics: Sleeve 6 has diameter almost similar todiameter of outer tubes 3 and 4, except that sleeve 6 is slightlylarger, the difference being about equal to twice the wall thickness oftubes 3 and 4. Sleeve 6 has corrugation similar to the corrugation ofthese tubes, particularly as to pitch of the helix, and wave length andamplitude of the corrugation pattern defined in any axial planeincluding the plane of the drawing are similar accordingly.

Sleeve 6 is now threaded on one of the tubes, e.g. tube 3. The cut awayportions at the ends of tubes 3 and 4 must leave sufficient spacebetween the tubes to permit that operation. However, the flexibility ofthe two pipe systems is instrumental here in permitting readily thebending of the end of one system out of the way. The sleeve 6 is nowscrewed onto tube 3 almost all the way, to leave substantially a widegap at first.

Next, a sleeve 7 is provided having diameter almost similar to thediameter of tubes 1 and 2, but being slightly smaller than those. Thedifference being also primarily determined by the thickness (twofold) ofthe walls of tubes 1 and 2. Also, the tube or sleeve 7 has corrugationsimilar to the corrugation of tubes 1 and 2. Sleeve 7 is now in effectthreaded almost all the way into one of the inner tubes, e.g. tube 1.Sleeve 7 is to protrude from tube 1 to such an extent only so as topermit gripping of the sleeve by a suitable bolt turning tool.

Next, tube 2 is placed coaxially and as close as possible to the end oftube 1, and now the sleeve 7 is, so to speak, unscrewed partially fromtube 1, and thereby screwed .into tube2 until approximately similarportions of sleeve 7, sl'ghtly less than half the length of the sleeve,are inserted in each of the tubes 1 and 2.-Thereafter, the ends properof tubes 1 and 2 are soldered or welded to sleeve 7. The remaining gapbetween the ends of tubes 1 and 2 is filled with material preferablyelectrically conductive material such as lead.

Subsequently, sleeve 6 that was partially screwed onto the outer tube 3,is now partially unscrewed therefrom and the right end of sleeve 6 willbe screwed onto tube 4. Again, sleeve 6 will be turned on its axis untilapproximately similar long end portions of tubing 3 and 4 are screwedinto and received in opposite ends of sleeve 6.

FIG. 1 illustrates in addition of particular roller tool 9 to worksleeve analogous to metal spinning pursuant to which the valleysof theicorrugation of sleeve 6 are forced into the valleys of the corrugationof tubes 3 and 4, to provide intimate contact and engagement between thesleeve ends and the tubes. The annular end faces of sleeve 6 aresubsequently welded to the otuer conductor tubes 3 and 4 at locations 10and 11.

The procedure outlined above is applicable to tube systems with morethan two tubes arranged in coaxial relationship. One will screw therespective sleeves into the tubes of one system, and subsequently thesleeves are turned in the reverse to screw them into the respectivetubes of the other system, beginning with a sleeve such as 7 forinterconnecting the innermost tubes of the two systems; the subsequentsleeves, such as 6 are progressively and threadedly turned tointerconnect the respectively aligned outer tubings, beginning with thesecond innermost up to the outermost.

The embodiment described with reference to FIG. 1

does, of course, depend upon a corrugation pattern that is helical, sothat sleeve insertion and positioning can be done by operation analogousto bolt threading. However, the invention is not restricted toapplication to tube systems with helical corrugation. The embodiment tobe described with reference to FIG. 2 assumes the threading to beannularly or parallel. It is not possible in such a case to thread anysleeve on or into the respective tube end, so that the two such tubesystems must be interconnected somewhat differently.

One coaxial tube system is denoted here with the reference numerals laand 3a; the other one bears reference numerals 2a and 4a, thecorrugation being circular parallel as assumed. In this case now thesleeves to be used for interconnection, are axially split twofold, sothat in the beginning, there are two separate halves for each sleeve. Asleeve is completed subsequently by axial welding the two halves alongtwo oppositely positioned welding seams.

Again, the tube system is prepared as before, so that the inner tubesproject from the respective outer tubes. Also as before, the pair ofaligned innermost tubes are to be interconnected first. It may beadvisable to weld the two inner tubes la and 2a together, but it isimportant that they are cut each to obtain corrugation pattern phasecoherency. Next, two sleeve halves 12 and 13 are laterally placed ontoand around the juxtaposed ends of tubes la and 2a, and they are weldedto obtain two axial welding seams such as 14, to complete thatparticular sleeve for jacketing and interconnecting the two ends oftubes 1a and 2a. In addition, the axial ends of the resulting sleeve arewelded respectively to tubes 1 and 2, there being annular welding seams15 and 16 accordingly. This procedure is repeated as far as the twoouter tubes 3 and 4 are concerned. The sleeve 17 is presented as twohalves, which are laterally placed from opposite sides onto tubes 3 and4, and through axial welding the connector sleeve 17 is completed.

It can readily be seen that more than two tubes in each system can be soconnected to the respective tubes of another coaxial tube system. It canalso be seen that the inventive method can be practiced even if theseveral tubes of different diameter have different types of corrugation,e.g. the innermost tubes may have circular corrugation, the outer tubesmay have helical corrugation (or vice versa). Sleeve halves with axialwelding are used in one case which does not preclude utilization ofsleeve threading as described for the other case.

It should also be mentioned finally that an apparent difference in phasecoherency as far as the corrugation pattern of tube 3 and 4 isconcerned, can readilybe taken up by axial expanding or contracting thecorrugation of the outer tubes, as they have axial flexibility, so as toreadily fit into the corrugation of the connector sleeve.

The invention is not limited to the embodiments described above but allchanges and modifications thereof not constituting departures from thespirit and scope of the invention are intended to be included.

We claim:

1. Method of interconnecting two coaxial tube systems, each having atleast two corrugated coaxial tubes comprising the steps of:

providing a first sleeve having similar corrugation as the respectiveinnermost tubes of the two systems to be interconnected and at slightlydiffering diameter than either of said innermost tubes placing the twoaxial ends of the first sleeve respectively adjacent to the end portionsof the said two innermost tubes and in concentric, axially overlappingas well as in corrugation matching, receiving and fitting relationthereto and for a certain span on each axial end of the first sleeve, sothat the ends of the innermost tubes on one hand, and the ends of thefirst sleeve on the other hand are placed into each other in telescopingrelationship to obtain innermost as sembled tubing constituted by saidfirst sleeve and by said innermost tubes, and having a phase coherentwave pattern in axial cross section as to their corrugation, said firstsleeve and said two innermost tubes together having four axial ends,said innermost tubing when assembled having only two of said axial endsoutwardly exposed while being radially aligned with wall portions ofthat part of the innermost tubing having the other two axial ends;bonding said axial end faces to the said wall portions of the innermosttubing having said other two axial end faces; disposing a second sleeveof slightly different diameter than the next, outer tubes of each systemin corrugation receiving relation to the axially displaced ends of theouter tubes and in telescoping relation therewith respectively adjacentthe two axial ends of the second sleeve; and

bonding the second sleeve to the outer tubes. 2. Method as in claim 1,wherein at least two respective tubes'of the two systems to beinterconnected as well as the respective sleeves are helicallycorrugated, for the sleeve to be threaded first onto one of the twotubes, and subsequently partially unscrewing the sleeve therefrom againwhile threading the other end of the sleeve into or onto the respectiveother tube.

3. Method as in claim 2, wherein the sleeve is threaded into the twotubes, there remaining a gap between the two tubes, covered from theinterior by the sleeve, and including the step of filling the gap withelectrically conductive material.

4. Method as in claim 1, wherein at least two respective tubes of thetwo systems to be interconnected have circular corrugation, therespective sleeve originally made of two or more axially divided parts,each placed in corrugation contour fitting relation to the ends of thetwo tubes, and axially welding the parts to combine them for providingthe sleeve.

5. Method as in claim 1, preceded by the step of preparing the twosystems so that in at least one end of the innermost tube projectsaxially beyond the end of the next outer tube.

6. Method as in claim 1, wherein at least two respective tubes of thetwo systems to be interconnected as well as the respective sleeves arehelically corrugated, for the sleeve to be threaded first into one ofthe two tubes, and subsequently partially unscrewing the sleevethere-from again while threading the other end of the sleeve onto therespective other tube.

7. Method as in claim 1, wherein the first sleeve has slightly smallerdiameter than the diameter of the two innermost tubes, causing the firstsleeve to be received adjacent opposite axial ends respectively by thetwo innermost tubes, said first mentioned bonding step established bybonding the axial ends of the two innermost tubes to the wall of thefirst sleeve.

8. Method as in claim 1, wherein the first sleeve has slightly largerdiameter than the diameters of the two innermost tubes, the telescopingincluding causing the ends of the two innermost tubes respectively to bereceived at opposite axial ends of the sleeve, said first mentionedbonding step established by bonding the axial ends of the sleeverespectively to the walls of the two innennost tubes.

9. Method as in claim 1, wherein at least two respective tubes of thetwo systems to be interconnected have circular corrugation, therespective sleeve originally made of two or more axially divided parts,each placed in corrugation contour fitting relation to the ends of thetwo tubes, and axially soldering the parts to combine them for providingthe sleeve. i g

10. Method as in claim 1, wherein the first sleeve axially overlays withrespect to said two tubes for more than one corrugation wavelength inaxial direction on each end of the first sleeve.

l I. III

1. Method of interconnecting two coaxial tube systems, each having atleast two corrugated coaxial tubes comprising the steps of: providing afirst sleeve having similar corrugation as the respective innermosttubes of the two systems to be interconnected and at slightly differingdiameter than either of said innermost tubes placing the two axial endsof the first sleeve respectively adjacent to the end portions of thesaid two innermost tubes and in concentric, axially overlapping as wellas in corrugation matching, receiving and fitting relation thereto andfor a certain span on each axial end of the first sleeve, so that theends of the innermost tubes on one hand, and the ends of the firstsleeve on the other hand are placed into each other in telescopingrelationship to obtain innermost assembled tubing constituted by saidfirst sleeve and by said innermost tubes, and having a phase coherentwave pattern in axial cross section as to their corrugation, said firstsleeve and said two innermost tubes together having four axial ends,said innermost tubing when assembled having only two of said axial endsoutwardly exposed while being radially aligned with wall portions ofthat part of the innermost tubing having the other two axial ends;bonding said axial end faces to the said wall portions of the innermosttubing having said other two axial end faces; disposing a second sleeveof slightly different diameter than the next, outer tubes of each systemin corrugation receiving relation to the axially displaced ends of theouter tubes and in telescoping relation therewith respectively adjacentthe two axial ends of the second sleeve; and bonding the second sleeveto the outer tubes.
 2. Method as in claim 1, wherein at least tworespective tubes of the two systems to be interconnected as well as therespective sleeves are helically corrugated, for the sleeve to bethreaded first onto one of the two tubes, and subsequently partiallyunscrewing the sleeve therefrom again while threading the other end ofthe sleeve into or onto the respective other tube.
 3. Method as in claim2, wherein the sleeve is threaded into the two tubes, there remaining agap between the two tubes, covered from the interior by the sleeve, andincluding the step of filling the gap with electrically conductivematerial.
 4. Method as in claim 1, wherein at least two respective tubesof the two systems to be interconnected have circular corrugation, therespective sleeve originally made of two or more axially divided parts,each placed in corrugation contour fitting relation to the ends of thetwo tubes, aNd axially welding the parts to combine them for providingthe sleeve.
 5. Method as in claim 1, preceded by the step of preparingthe two systems so that in at least one end of the innermost tubeprojects axially beyond the end of the next outer tube.
 6. Method as inclaim 1, wherein at least two respective tubes of the two systems to beinterconnected as well as the respective sleeves are helicallycorrugated, for the sleeve to be threaded first into one of the twotubes, and subsequently partially unscrewing the sleeve there-from againwhile threading the other end of the sleeve onto the respective othertube.
 7. Method as in claim 1, wherein the first sleeve has slightlysmaller diameter than the diameter of the two innermost tubes, causingthe first sleeve to be received adjacent opposite axial endsrespectively by the two innermost tubes, said first mentioned bondingstep established by bonding the axial ends of the two innermost tubes tothe wall of the first sleeve.
 8. Method as in claim 1, wherein the firstsleeve has slightly larger diameter than the diameters of the twoinnermost tubes, the telescoping including causing the ends of the twoinnermost tubes respectively to be received at opposite axial ends ofthe sleeve, said first mentioned bonding step established by bonding theaxial ends of the sleeve respectively to the walls of the two innermosttubes.
 9. Method as in claim 1, wherein at least two respective tubes ofthe two systems to be interconnected have circular corrugation, therespective sleeve originally made of two or more axially divided parts,each placed in corrugation contour fitting relation to the ends of thetwo tubes, and axially soldering the parts to combine them for providingthe sleeve.
 10. Method as in claim 1, wherein the first sleeve axiallyoverlays with respect to said two tubes for more than one corrugationwavelength in axial direction on each end of the first sleeve.